Barrett's Esophagus (BE) is a condition of the esophagus that is pre-cancerous, a precursor to cancer of the esophagus. The standard practice for diagnosing Barrett's Esophagus uses a flexible endoscopy procedure, often with the esophageal lumen insufflated with air. A normal esophagus is usually light pink in color, while the stomach appears slightly darker pink. Barrett's Esophagus usually manifests itself as regions of slightly darker pink color above the lower esophageal sphincter (LES) that separates the stomach from the esophagus.
It is preferable to diagnose BE early, since this condition has been found to be a precursor of esophageal adenocarcinoma. Accordingly, it would be desirable to provide a general screening procedure for the condition, even though doing so would require evaluating the condition of the esophagus in millions of people with chronic heartburn and gastric reflux. However, Barrett's Esophagus and early stage cancers can occur without telltale symptoms, so mass screenings have been proposed as the only viable approach to identify the condition as early as possible to enable treatment and avoid the onset of or provide a curative therapy for the cancerous condition. Unfortunately, the numbers of people that are likely candidates for esophageal screening and the current cost associated with the practice of flexible endoscopy performed by a physician compared to the reimbursement associated with such mass screenings make this solution currently impractical because of the expense involved.
What is needed is a much more efficient and cost effective approach for identifying those people having Barrett's Esophagus. Only a doctor can perform an examination of the esophagus using a conventional flexible endoscope, and the procedure is thus relatively expensive. It would be preferable to develop a different scanning technique that need not be performed by a physician, but instead, can be performed by a trained medical technician or nurse. Indeed, it would also be desirable to automate the evaluation of images produced by imaging the internal surface of the esophagus just proximal of the LES so that the existence of Barrett's Esophagus can be automatically detected either in real time during the scanning operation or immediately thereafter.
To facilitate mass screenings of individuals who may be afflicted with Barrett's Esophagus, it would be desirable to employ a screening device that can readily be introduced into the esophagus, without invoking any gag reflex. Ideally, the scanning device should be embodied in a capsule-shaped housing so that it can simply be swallowed with a glass of water. Accordingly, the device must be sufficiently small in size to enable it to be swallowed by most patients. Further, although such a device might be reusable if properly sterilized, it may be desirable to employ a screening device that is sufficiently low in cost as to be disposable after a single use.
The above-noted earlier related application discloses an approach for monitoring a position in a person's esophagus of an endoscope that is well-suited for providing images that can be used to evaluate the condition of the esophagus and thereby detect BE. In this earlier approach, a tether attached to a capsule endoscope that includes an imaging device passes over a wheel that rotates as the capsule is moved axially within the esophagus, to enable the relative position of the capsule in the esophagus to be continually monitored. The axial position of the capsule is important so that the locations of regions, which may be of interest in images of the inner surface of the esophagus, can be identified and to enable the axial scaling of any panoramic images taken. However, the measurement of the axial position depends upon the frictional contact between the tether and the measurement wheel. There are three reasons why this method may not produce sufficiently accurate results. In this earlier described approach, the tether must be kept under tension, and the measurement technique relies on no-slip friction between the measurement wheel and the moving tether. Slippery saliva and mucus within the person's mouth and esophagus can adhere to the tether creating slippage between the measurement wheel that is rotated and the tether. In addition, the clinician performing the procedure may want to feel the progression of the tethered capsule scope as it passes through the lower esophageal sphincter and other parts of the esophagus, and the additional applied tension produced by the measurement wheel (which was disclosed as a pinch wheel) is likely to interfere with that feel. Similarly, the clinician may want to move the capsule scope up and down within the esophagus in a repeated manner, which will likely introduce measurement error in a mechanical system that is based on the friction between the measurement wheel and the tether. Any hysteresis in the measurement can be a further source of error.
Accordingly, a better technique for monitoring the axial position of the capsule scope is desired. The approach that is used should monitor the movement of the capsule by detecting the motion of the tether without actual contact between the tether and the axial position monitoring apparatus. The presence of saliva and mucus should have minimal impact on the monitoring technique used, and the feel as the capsule scope is moved up and down should be readily experienced by the clinician without interference from the apparatus used to monitor the position of the capsule.